================================================================== BUG: KASAN: use-after-free in hlist_add_head include/linux/list.h:814 [inline] BUG: KASAN: use-after-free in enqueue_timer+0x9e/0x2c0 kernel/time/timer.c:541 Write of size 8 at addr ffff8881d41031c8 by task syz.1.659/2674 CPU: 1 PID: 2674 Comm: syz.1.659 Not tainted 5.4.292-syzkaller-00021-gcd8e74fa0fa3 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: __dump_stack+0x1e/0x20 lib/dump_stack.c:77 dump_stack+0x15b/0x1b8 lib/dump_stack.c:118 print_address_description+0x8d/0x4c0 mm/kasan/report.c:384 __kasan_report+0xef/0x120 mm/kasan/report.c:516 kasan_report+0x30/0x60 mm/kasan/common.c:653 __asan_report_store8_noabort+0x17/0x20 mm/kasan/generic_report.c:137 hlist_add_head include/linux/list.h:814 [inline] enqueue_timer+0x9e/0x2c0 kernel/time/timer.c:541 __internal_add_timer kernel/time/timer.c:554 [inline] internal_add_timer+0x208/0x3e0 kernel/time/timer.c:604 __mod_timer+0x5ab/0x1150 kernel/time/timer.c:1065 mod_timer+0x1f/0x30 kernel/time/timer.c:1117 tun_flow_init drivers/net/tun.c:1446 [inline] tun_net_init+0x2ba/0x580 drivers/net/tun.c:1055 register_netdevice+0x1c4/0x12a0 net/core/dev.c:9139 tun_set_iff+0x812/0xe00 drivers/net/tun.c:2922 __tun_chr_ioctl+0x771/0x18a0 drivers/net/tun.c:3187 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:3470 do_vfs_ioctl+0x753/0x13f0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xe1/0x120 fs/ioctl.c:747 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 RIP: 0033:0x7f44e34b9969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f44e1b22038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f44e36e0fa0 RCX: 00007f44e34b9969 RDX: 0000200000000200 RSI: 00000000400454ca RDI: 0000000000000004 RBP: 00007f44e353bab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f44e36e0fa0 R15: 00007fff4b817348 Allocated by task 2625: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] __kasan_kmalloc+0x162/0x200 mm/kasan/common.c:529 kasan_slab_alloc+0x12/0x20 mm/kasan/common.c:537 slab_post_alloc_hook mm/slab.h:584 [inline] slab_alloc_node mm/slub.c:2829 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0xe2/0x270 mm/slub.c:2842 getname_flags+0xb9/0x500 fs/namei.c:141 getname fs/namei.c:212 [inline] do_symlinkat+0x48/0x3b0 fs/namei.c:4292 __do_sys_symlinkat fs/namei.c:4317 [inline] __se_sys_symlinkat fs/namei.c:4314 [inline] __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Freed by task 2625: save_stack mm/kasan/common.c:70 [inline] set_track mm/kasan/common.c:78 [inline] kasan_set_free_info mm/kasan/common.c:345 [inline] __kasan_slab_free+0x1c3/0x280 mm/kasan/common.c:487 kasan_slab_free+0xe/0x10 mm/kasan/common.c:496 slab_free_hook mm/slub.c:1455 [inline] slab_free_freelist_hook+0xb7/0x180 mm/slub.c:1494 slab_free mm/slub.c:3080 [inline] kmem_cache_free+0x10c/0x2c0 mm/slub.c:3096 putname fs/namei.c:262 [inline] do_symlinkat+0x339/0x3b0 fs/namei.c:4310 __do_sys_symlinkat fs/namei.c:4317 [inline] __se_sys_symlinkat fs/namei.c:4314 [inline] __x64_sys_symlinkat+0x7b/0x90 fs/namei.c:4314 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 The buggy address belongs to the object at ffff8881d4102200 which belongs to the cache names_cache of size 4096 The buggy address is located 4040 bytes inside of 4096-byte region [ffff8881d4102200, ffff8881d4103200) The buggy address belongs to the page: page:ffffea0007504000 refcount:1 mapcount:0 mapping:ffff8881f5d01900 index:0x0 compound_mapcount: 0 flags: 0x8000000000010200(slab|head) raw: 8000000000010200 dead000000000100 dead000000000122 ffff8881f5d01900 raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL) set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook mm/page_alloc.c:2165 [inline] prep_new_page+0x35e/0x370 mm/page_alloc.c:2171 get_page_from_freelist+0x1296/0x1310 mm/page_alloc.c:3794 __alloc_pages_nodemask+0x202/0x4b0 mm/page_alloc.c:4894 alloc_slab_page+0x3c/0x3b0 mm/slub.c:343 allocate_slab mm/slub.c:1683 [inline] new_slab+0x93/0x420 mm/slub.c:1749 new_slab_objects mm/slub.c:2505 [inline] ___slab_alloc+0x29e/0x420 mm/slub.c:2667 __slab_alloc+0x63/0xa0 mm/slub.c:2707 slab_alloc_node mm/slub.c:2792 [inline] slab_alloc mm/slub.c:2837 [inline] kmem_cache_alloc+0x12c/0x270 mm/slub.c:2842 getname_flags+0xb9/0x500 fs/namei.c:141 getname fs/namei.c:212 [inline] do_rmdir+0xcb/0x480 fs/namei.c:4055 __do_sys_unlinkat fs/namei.c:4252 [inline] __se_sys_unlinkat fs/namei.c:4246 [inline] __x64_sys_unlinkat+0xb6/0xe0 fs/namei.c:4246 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x5c/0xc1 page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1176 [inline] __free_pages_ok+0x7e4/0x910 mm/page_alloc.c:1438 free_the_page mm/page_alloc.c:4956 [inline] __free_pages+0x8c/0x110 mm/page_alloc.c:4962 kfree+0x1ca/0x260 mm/slub.c:4068 kvfree+0x4c/0x50 mm/util.c:625 netdev_freemem+0x3f/0x60 net/core/dev.c:9583 netdev_release+0x7f/0xb0 net/core/net-sysfs.c:1743 device_release+0x70/0x1a0 drivers/base/core.c:1776 kobject_cleanup lib/kobject.c:716 [inline] kobject_release lib/kobject.c:747 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x1fe/0x2c0 lib/kobject.c:764 put_device+0x1f/0x30 drivers/base/core.c:3010 free_netdev+0x27e/0x320 net/core/dev.c:9746 tun_set_iff+0x87c/0xe00 drivers/net/tun.c:2924 __tun_chr_ioctl+0x771/0x18a0 drivers/net/tun.c:3187 tun_chr_ioctl+0x2a/0x40 drivers/net/tun.c:3470 do_vfs_ioctl+0x753/0x13f0 fs/ioctl.c:47 ksys_ioctl fs/ioctl.c:742 [inline] __do_sys_ioctl fs/ioctl.c:749 [inline] __se_sys_ioctl fs/ioctl.c:747 [inline] __x64_sys_ioctl+0xe1/0x120 fs/ioctl.c:747 do_syscall_64+0xcf/0x170 arch/x86/entry/common.c:290 Memory state around the buggy address: ffff8881d4103080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881d4103100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881d4103180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881d4103200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881d4103280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================